Cameron's pro-marriage tax plan comes under Tory fire

David Cameron is facing internal opposition over his plans to give tax breaks to married couples, with frontbenchers pushing a rival plan to raise child benefit for all children instead.

The new Tory leader has repeatedly argued that marriage is an institution deserving of taxpayer support, a traditionalist Tory view of the family which has appeared at odds with his liberal position on other issues.

But modernisers are arguing that an increase in child benefit - which goes to all parents, regardless of whether they are rich or poor and married or not - would be a fairer way to support families. It could also appeal to the middle-class mothers who earn too much to qualify for Labour's tax credits but feel entitled to state help.

Paul Goodman, the shadow minister for childcare, is understood to have drawn up plans to boost child benefit as an alternative option, alongside proposals Cameron made to reintroduce tax breaks for marriage - for example, by allowing mothers who do not work to transfer their unused tax allowance to their working husbands, or give tax relief for childcare.

A senior Tory source said there were 'various options' now on the table for family policy, of which tax breaks for married couples was only one: 'David mentioned the tax cuts for childcare and transferable allowances, but he didn't say they were the only options.'

The Child Poverty Action Group, which is launching a campaign today for an increase in child benefit, has met Goodman along with other senior Tories and discussed child benefit with them. A spokesman said it welcomed the idea: 'We would agree with it, if they have got the money to do it - and if they are not going to take the money from elsewhere, such as tax credits.'

A recent report by the rightwing thinktank, the Centre for Policy Studies, concluded that Tory backbenchers were now worried that tax breaks for married couples would alienate single mothers and cohabiting parents.

Goodman declined to comment on the child benefit proposal, saying it was too early to reach conclusions.